| Piereis | |
| Name Local: | Πιερείς |
| Type: | municipal unit |
| Periph: | East Macedonia and Thrace |
| Periphunit: | Kavala |
| Pop Municunit: | 3470 |
| Population As Of: | 2021 |
| Area Municunit: | 143.4 |
| Elevation: | 190 |
| Coordinates: | 40.85°N 30°W |
| Licence: | ΚΒ |
Piereis (Greek, Modern (1453-);: Πιερείς) is a former municipality in the Kavala regional unit, East Macedonia and Thrace, Greece. Since the 2011 local government reform it is part of the municipality Pangaio, of which it is a municipal unit.[1] The municipal unit has an area of 143.402 km2.[2] Population 3,470 (2021). The seat of the municipality was in Moustheni.